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The ERA-Interim analysis is an improvement over the original analysis which did not have as many observations. The scientific content of the IFS operational model at that time was significantly different to the more modern OpenIFS. A rough proxy for the how the forecast at the time performed would be to run OpenIFS at T255, the resolution of the initial data.
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As OpenIFS is a spectral model, the 'T' number refers to the triangular truncation is spectral space. Equivalent grid-pt resolutions are: |
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- What's the impact of the different 'lead times' on the forecast of the storm (i.e. starting from different dates)?
- What's the impact of resolution on the forecast of the storm: both for it's development and impact over areas worse hit in Europe?
Reduce the timestep of the model - does this improve or worsen the forecast?
Reduce the gravity wave drag - how does this affect the forecast in the upper and lower levels?
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Edit the source code to half the gravity wave drag coefficient File: ifs/phys_ec/sugwd.F90, change:
to:
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Increase the precipitation auto conversion rate - what impact does this have?
Expand title How to change the code (click here to expand…) Edit the source code to increase the auto conversion rate by 20%
File: ifs/phys_ec/sucldp.F90, change:
Code Block line 123: RKCONV=1._JPRB/6000._JPRB ! 1/autoconversion time scale (s)
to:
Code Block line 123: ! RKCONV=1._JPRB/6000._JPRB ! 1/autoconversion time scale (s) line 124: RKCONV=1.2_JPRB/6000._JPRB ! default scaled by 20%: 1/autoconversion time scale (s)Change the surface transfer coefficient in the turbulence scheme
Expand Reduce the coefficient by 20%.
Alter surf/module/surfexcdriver_ctl_mod.F90 from :
Code Block line 671: DO JL=KIDIA,KFDIA line 672: IF (JTILE == IFRMAX(JL)) THEN line 673: PKHLEV(JL)=ZKHLEV(JL) line 674: ENDIF line 675: ENDDOto:
Code Block line 671: DO JL=KIDIA,KFDIA line 672: IF (JTILE == IFRMAX(JL)) THEN line 673: PKHLEV(JL)=ZKHLEV(JL) line 674: ENDIF ! reduce surface transfer coeff by 20% in turbulence scheme ! for stockholm MSc course experiments ZCFMTI(JL,JTILE)=0.8_JPRB*ZCFMTI(JL,JTILE) line 675: ENDDO
Reduce (halve) the asymptotic mixing length scale (K)
Expand title How to change the model code (click here to expand) For this change, two files need to be edited:
Code Block title ifs/phys_ec/suvdf.F90 line 53: RLAM = 75.0_jprb !! 150._JPRB: reduce to 75mand:
Code Block title ifs/phys_ec/vdfexcu.F90 ZKLEN = 75.0_jprb !! 150.0_JPRB ! asymptotic K length scale troposphere - Reduce to 75m
Further reading
Ulbrich et al., 2001, Weather, 56, 70-80
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